Fear and anxiety response Oxytocin is typically remembered for the effect it has on prosocial behaviors, such as its role in facilitating trust and attachment between individuals. Consequently, oxytocin is often referred to as the “love hormone.[88] However, oxytocin has a larger, and more complex role than solely enhancing prosocial behaviors. Oxytocin also plays a role in enhancing fear and anxiety. There is a consensus that oxytocin has a modulatory effect on fear and anxiety; that is, oxytocin does not directly elicit fear or anxiety.[89] There are two dominant theories explaining the role oxytocin plays in fear and anxiety. One theory states that oxytocin increases approach/avoidance to certain social stimuli. The second theory states that oxytocin increases the salience of certain social stimuli, causing the animal or human to pay closer attention to socially relevant stimuli.[90] Individuals who receive an intranasal dose of oxytocin identify facial expressions of disgust faster than individuals who do not receive oxytocin.[90] Facial expressions of disgust are evolutionarily linked to the idea of contagion. Thus, oxytocin increases the salience of cues that imply contamination, which leads to a faster response because these cues are especially relevant for survival. In another study, after administration of oxytocin, individuals displayed an enhanced ability to recognize expressions of fear compared to the individuals who received the placebo.[91] Oxytocin modulates fear responses by enhancing the maintenance of social memories. Rats that are genetically modified to have a surplus of oxytocin receptors display a greater fear response to a previously conditioned stressor. Oxytocin enhances the aversive social memory, leading the rat to display a greater fear response when the aversive stimulus is encountered again.[89] Gender differences To make the role of oxytocin even more complex, it has been shown that oxytocin differentially affects males and females. Females who are administered oxytocin are overall faster in responding to socially relevant stimuli than males who received oxytocin.[92][93] Additionally, after the administration of oxytocin, females show increased amygdala activity in response to threatening scenes; however, males do not show increased amygdala activation. This phenomenon can be explained by looking at the role of gonadal hormones, specifically estrogen, which modulate the enhanced threat processing seen in females. Estrogen has been shown to stimulate the release of oxytocin from the hypothalamus and promote receptor binding in the amygdala.[93] Effect in predictable and unpredictable stimuli Oxytocin increases defensive responding to unpredictable stimuli, but not to predictable stimuli. This result leads to the assumption that oxytocin’s effect is context-dependent. Thus, oxytocin may reinforce prosocial behaviors after an initial bond is formed, but may enhance defensive behaviors to unfamiliar individuals.[88] Oxytocin is beneficial because it can either enhance social bonding or promote defensive behaviors depending on the situation.[88] It would not be adaptive if oxytocin consistently enhanced social approach and other prosocial behaviors, especially in uncertain and potentially dangerous social contexts. Fear and anxiety are typically thought to be maladaptive, as these traits often underlie various psychological disorders. However, it is important to note that both fear and anxiety responses help to protect an individual. These emotions render environmental cues more important, leading to a greater likelihood the individual or animal will acknowledge the potential threat. Ultimately this process leads to a greater chance of survival.
Posted on: Tue, 11 Mar 2014 08:26:42 +0000